Keeping Tabs On Transcranial Direct Current Stimulation

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First, participants donned EEG monitors and performed a challenging cognitive control task specifically designed to trip them up. “We saw a beautiful burst of low-frequency activity [from the medial-frontal cortex] right after someone made a mistake,” said Reinhart. “But it was deficient in our patients with schizophrenia.”

In healthy individuals, these theta waves were steady and synchronized, but in people with schizophrenia, the waves were weak and disorganized, suggesting that they were having a harder time processing the mistake. And the subjects’ behavior bore that out—the healthy subjects slowed down by a few milliseconds when they made mistakes and did better in the next round, while the subjects with schizophrenia did not.

After tDCS, the picture was dramatically different. The electrical stimulation to the scalp significantly improved the strength and synchrony of the brain waves in both groups but most notably in people with schizophrenia. “The results of our study clearly indicate that it is possible to restore error-monitoring in people with schizophrenia with tDCS,” said Park.

One unusually well-designed study, he said, was from the University of Lyon in France, in which 30 people with schizophrenia reported that after TDCS, they heard voices about 30 percent less than before. The researchers followed up with the patients, and the treatment was still working, even after three months.

Frohlich decided that the schizophrenia study was so potentially life-changing for patients that it had to be replicated — and improved upon — as quickly as possible. According to the National Institutes of Health, about 1 percent of Americans have schizophrenia; many of them are too sick to work or even talk lucidly with their doctors about treatment. Antipsychotic medication helps some, but it has serious side effects. A 2013 study estimated that the costs of schizophrenia — from treatment to caregiving and unemployment — are about $4 billion a year in the U.S.

Results: Auditory verbal hallucinations were robustly reduced by tDCS relative to sham stimulation, with a mean diminution of 31% SD=14; d=1.58, 95% CI=0.76–2.40. The beneficial effect on hallucinations lasted for up to 3 months. The authors also observed an amelioration with tDCS of other symptoms as measured by the Positive and Negative Syndrome Scale d=0.98, 95% CI=0.22–1.73, especially for the negative and positive dimensions. No effect was observed on the dimensions of disorganization or grandiosity/excitement.

Conclusions: Although this study is limited by the small sample size, the results show promise for treating refractory auditory verbal hallucinations and other selected manifestations of schizophrenia.